a) Field of the Invention
The invention is directed to a process and apparatus for pressing and drying pasta by extrusion via a die and subsequent drying in a continuous flow drier.
b) Background and Related Art
The principal distinction between processes and apparatuses for the production of so-called long goods, e.g. spaghetti, and processes and apparatuses for the production of so-called short goods, e.g. horns and other pasta cut to short length, consists in that they can be treated in further processing as bulk goods.
On an industrial scale, long goods, i.e. spaghetti, are still produced in that the pasta strands which are delivered continuously from the mold or die are transferred to a rod, cut to a predetermined length on these rods, and guided into a drier on these rods. The pasta strands are then cut to the desired length of spaghetti following the drier.
Short goods are guided through the drying means in a manner known per se with a proportionate mechanical expenditure on receiving and transporting members and liftover devices. The advantage over long goods, e.g. spaghetti, consists in that these short goods can be cut to length already at the extrusion die.
Therefore, the problem arises for both short and long goods of reducing the mechanical outlay.
In principle, technical solutions which are costly and possibly also complicated, but which are also spatially compact and therefore attractive, are justified for large-volume industrial fabrication. But within the framework and idea of a decentralization of foodstuffs manufacturing and the reduction in production output which this entails these solutions may be too complicated and expensive.
Tendencies in technical development over the last decades led toward gigantism with all of the ecological disadvantages recognized today. For this reason, thinking is changing direction again away from gigantism toward the goal of small operations in situ so that marketing organization with all the associated transportation problems and loading of the environment can likewise be reduced in a corresponding manner.
It is also in view of these considerations that the present Inventor has set himself the above-mentioned task.
Regarded in a purely physical sense, pasta products can be dried e.g. within a half hour.
The present Applicant achieved a first major breakthrough with the idea of complete control of a section-by-section drying climate control and the simultaneous use of a drying temperature of 80.degree. C. to 100.degree. C. for long pasta. It was possible to reduce the drying time to two to six hours and even to one hour, at least in laboratory tests. However, all findings confirmed that in the case of long goods the drying technology not only causes more problems, but also requires special general conditions. Yet only the method of drying long pasta products on rods achieved commercial success. Ideas for drying long goods without the use of rods have not had practical success for technical reasons. In principle, the technical means must conform to the requirements of the biological, biochemical and physical laws of the product to be processed.
The drying of pasta aims not only at the inner quality of the product, e.g. cooking properties, texture (e.g. al dente) or color, tensile strength, etc., but especially also at obtaining the straightest possible shape of an individual piece of long goods, particularly spaghetti. This is not so much because of consumer requirements as that it constitutes a basic precondition for the smooth functioning of the automatic packaging machinery.
The product is highly flexible and still deformable immediately after pressing and can therefore be hung on rods in the well-known U-shape with the use of simple means and can be left in this position until final drying. Long, straight pasta products are obtained in this way provided no gross errors are made in drying.
The problem of drying long goods on rods in itself is solved in technical respects.
A problem resulted when the drying temperature was increased in that substantially greater demands were made on the work materials of the operating arrangement as well as the mechanical means, particularly the mechanically moved parts, which increased the cost of producing an entire pasta line.
Short pasta or short goods have become associated over time with a special characteristic.
Short goods are pressed via a circular die and cut to the desired packaging length with a rotating knife directly at the die. After they are cut, the short goods usually fall into a conveyor which lifts them over and feeds them to a rotary distributor which spreads out the goods in a uniform bulk layer on the drying surface of a vibrating pre-drier.
After the vibrating pre-drier the short goods already have considerable stability of shape so that they can be dried to a moisture content of less than 13% with greater layer thicknesses on different drying belts.
In contrast, long goods are not cut directly at the die, but only after the pasta strands are hung on the rods in the typical U-shape at a distance from the extrusion die of approximately 0.5 to 1.5 m depending on the specific construction, resulting in a constant alternation between hanging and cutting, etc. The goods then remain on the rods, often until immediately before the definitive cutting of the dried product for the packaging length. The pasta remain on the rods in a stacker for many hours particularly to achieve good stabilization. The external shape seems almost to compel these particular drying techniques. Formerly, it was unthinkable to dry the long goods as a bulk layer.